Smiths joins Birmngham U. to develop next-generation IMS systems

Published 29 January 2007

Ion mobility spectrometery has already proven itself in Smiths Detection’s Sentinel portals, but all agree that improvement in chemical detection is neccesary; £1 million project will take a close look at ionization chemistry

The trace portal detection systems proposed and installed by Smiths Detection are still a work in progress — DHS has noted that the portals are difficult to maintain due to the excessive dustiness of airports — but the ion mobility spectrometery (IMS) technology behind them offers some of the best hope around on the chemical detection front. Smiths cannot do it alone, however. That is why the company is now working closely with Birmingham University on a £1 million project to develop even more sensitive systems than the company has so far manufactured. Key to the effort is difficult laboratory work, and so Smiths has contributed £400,000 in equipment and expertise.

IMS works by creating positively or negatively charged ions at atmospheric pressure by a radioactive source or a corona discharge. Certain ions are selected based on their polarity and pulsed into a drift tube where they migrate under the influence of the electric field along a linear potential gradient. How fast they do so depends on the particular ion species and the mass, shape, ion structure, and the drift gas. Then, when air is introduced to the mix, the substance being sought — if present — may react with the initial ions in the drift tube to produce further ions of their own unique mobility. Measuring this movement allows the identification and quantification of the suspect substance.

Unfortunately, this method remains immature, with some calling the Smiths Sentinel portals “first-generation and one-dimensional.” According to a British National Resource Council report, “currently deployed systems have limitations specific to the physics and chemistry of their operation.” Looking for the second generation IMS, the Birmingham researchers will conduct fundamental research as to the key chemical processes employed in IMS and, in particular, those occurring in the latest generation of drift tube systems being developed by Smiths. Much of the work will involve coupling the IMS to an ion trap mass spectrometer to investigate the ionisation chemistry — the use of chemical dopant and the mode of operation.

-read more in this The Engineer report